Space Sunday: drills, telescopes, pictures and doubts

In March I reported that NASA’s Mars Science Laboratory rover Curiosity had taken an important step in recovering its ability to drill into Martian rocks to collect samples. Now it looks like drilling operations could be resuming.

Use of the sample-gathering drill was suspended in December 2016, after problems were encountered with the drill feed mechanism – the motor used to extend the drill head between two “contact posts” designed to steady the rover’s turret during drilling operations. In particular, there was concern that continued use of the drill feed mechanism would see it fail completely, ending the use of the drill.

Since then, engineers have been trying to develop a means of using the drill without and reliance on the drill feed mechanism, and at the end of February 2018, a new technique was tested. Called Feed Extended Drilling, or FED, it keeps the drill bit and head extended, and uses the weight of the rover’s robot arm and turret to push the bit into a target rock. This is harder than it sounds,as it requires the weight of the rover’s arm to provide the necessary pressure to help push the drill bit into a rock – something it is not designed to do, and might actually break the drill bit or cause it to become stuck. However, the rover passed the February test with flying colours.

This success meant that engineers could focus on recovering the drill’s percussive action. This assists in both helping the drill cut into a rock and in breaking the contact area under the bit up into a fine powder that can be collected by the collection tube surrounding the bit.

A close-up of the drill mechanism. In the centre is the hollow drill bit, which cuts into rock and gathers sample powder. The drum at the base of the drill is the first part of the sample collection mechanism. Also of this used to be extended up against a rock sample by the drill feed mechanism. Just visible cutting across the bottom right corner of the image is one of the two contact posts. The second post can be seen in part in the top right corner of the image. These are used to hold the rover’s robot arm steady against a target rock surface while the drill is extended for sample-gathering operations. Credit: NASA

On Saturday, May 19th, and following further tests using Curiosity’s Earth-base test bed twin, the command was sent to Mars for Curiosity to carry out a second drilling test using both the FED approach and with the drill percussive action enabled. Unlike the February test, however, this one has an additional goal: to actually recover a special sample of rock.

For the last couple of months, the rover has been making its way along a feature on “Mount Sharp” dubbed “Vera Rubin Ridge”, toward an uphill area enriched in clay minerals that the science team is eager to explore. In doing so, the rover passed a distinct rock formation that could fill a gap in the science team’s knowledge about Mount Sharp and its formation.

Testing the FED / percussion approach to drilling on Earth using Curiosity’s test-bed “twin”. Not how the drill head (centre) is fully extended, so the contact posts cannot be used. Forward pressure on the drill is being provided entirely by the rover’s robot arm. Credit: NASA/JPL

Given the progress made in trying to get the drill working again, the decision was made to reverse Curiosity’s course in mid-April and drive back to the rock formation in the hope that the May 19th test could gather a sample from it. Commenting on the decision, Curiosity principal scientist Ashwin Vasavada said, “Every layer of Mount Sharp reveals a chapter in Mars’ history. Without the drill, our first pass through this layer was like skimming the chapter. Now we get a chance to read it in detail.”

If the new technique has allowed Curiosity to gather a sample – at the time of writing this article, NASA had yet to provide an update on the operation – the engineering team will immediately begin testing a new process for delivering that sample to the rover’s internal laboratories. This is again a complex process, which in the past has involved the drill feed mechanism to transfer material gathered by the drill to another mechanism called CHIMRA (Collection and Handling for In-Situ Martian Rock Analysis), also mounted on the rover’s turret. CHIMRA sieves and sorts the material, grading it by size and coarseness before transferring it to the rover’s science suite, located in Curiosity’s main body.

Curiosity’s “fingers”: the five instruments on the rover’s turret, including the drill with the feed mechanism motors behind it and the two angled contact posts clearly visible, and the CHIMRA system used for sieving and sorting sample material gathered by both its own scoop (for surface material) and the drill (for rock samples). Credit: NASA

Success with both the drilling operation and same transfer will mean – allowing for fine-tuning and other adjustments – the drill could be re-entering regular use in the near future.

WFIRST and OCO to Survive?

In February 2018, NASA Fiscal Year 2019 budget gained its first public airing (see here for more). It contained the surprising revelation that the Wide Field Infra-Red Survey Telescope (WFIRST) was to receive no funding beyond 2018, effectively cancelling it.

Billed as a cousin to the Hubble Space Telescope, WFIRST uses an existing 2.4 metre primary mirror originally made for Hubble, but which has a shorter a shorter focal length. This, coupled with no fewer than 18 sensors built into the telescope’s camera (Hubble only has a single sensor), would give WFIRST the ability to image the sky with the same sensitivity as Hubble, but over an area 100 times larger. To put this in perspective: where Hubble can produce a poster for your living room wall with a single image, WFIRST would be able to decorate the entire side of your house.

WFIRST’s layout and instruments. Credit: NASA

The White House rationale for cancelling WFIRST was that it “overlaps” the James Webb Space Telescope (JWST), and that “good” science can be conducted with “cheaper” missions – an ironic statement given that despite a small increase in projected cost, WFIRST would be one of the most cost-effective NASA deep space missions, thanks to its use of available elements.

It now appears this latter fact hasn’t been lost of Congress. On May 17th, 2018 House appropriators approved a spending bill that restores US$150 million out of a requested US $302 million funding for WFIRST. It is now anticipated that the Senate will also approve the reinstatement of funding. While not the full amount, it is enough to keep WFIRST moving forward.

Also targeted for cancellation in the FY 2019 budget were a number of Earth Science programmes, including the Orbiting Carbon Observatory (OCO) 3 science suite, intended to provide global space-based observations of atmospheric carbon dioxide (CO2). Already built, and intended for deployment to the space station OCO 3’s cancellation appeared particularly pointless. However, during a NASA Town Hall meeting on May 18th, 1028, newly appointed Administrator James Bridenstine stated OCO 3 will fly to the ISS in January 2019.

TESS Returns Test Image

NASA’s new exoplanet hunter, the Transiting Exoplanet Survey Satellite (TESS), has taken two important steps towards reaching operational status.

Launched from Cape Canaveral Air Force Station atop a SpaceX Falcon 9 booster on Wednesday, April 18th. TESS is en route to a “2:1 lunar resonant orbit“, balancing it between the gravitational effects of the Moon and Earth, while it will remain in a stable observational position that could last for decades while it seeks exoplanets.

An artist’s impression of TESS passing by the Moon on May 17th, 2018. NASA Goddard Space Flight Centre

On May 17th, 2018, TESS completed a lunar flyby, coming to within 8,000 kilometres (5,000 miles) of the Moon’s surface in a gravity assist manoeuvre designed to push it towards its final Earth / Moon orbit without using any fuel. A final thruster burn is due to take place n May 30th to establish TESS in this final orbit.

In the meantime, as part of the commissioning and calibration process for the observatory’s imaging and science systems, the TESS science team ordered one of the four cameras on the satellite to take a two-second test exposure. Focused on the southern constellation Centaurus, the image reveals more than 200,000 stars. It is just a small sample of the images TESS will be able to capture. With all four cameras operational, it will cover more than 400 times as much sky during its initial two-year primary mission.

This test image from one of the four cameras aboard the Transiting Exoplanet Survey Satellite (TESS) captures a swath of the southern sky along the plane of our galaxy. Revealing more than 200,000 stars, the image is centred in the constellation Centaurus and includes dark tendrils from the Coalsack Nebula and the bright emission nebula Ced 122 (upper right). The bright star at bottom centre is Beta Centauri. Credit: NASA / MIT

Calibration of the camera and other systems on the observatory will continue through May and into June. In is anticipated that the first science-quality image, referred to as a “first light” image, will be released in June.

Pessimistic Outlook Voiced for Commercial Space Stations

In announcing the FY 2019 NASA Budget, the White House wanted to phase-out the International Space Station by 2025, in favour of developing a sustained commercial presence in low-Earth orbit. To help with this, NASA is expected to provide some $900 million through to 2023 to assist companies in developing their own orbital facilities.

However, a study put before a congressional hearing on May 17th, 2018 by the Institute for Defense Analysis’ Science and Technology Policy Institute suggests the future for commercial space stations is less than positive. The study notes that it is unlikely that a commercial space station could generate a profit in 2025, the year the Trump Administration would like to end federal funding of the ISS – and it will take longer for any such station to reach a level of commercial viability.

A report from the Institute for Defense Analysis’ Science and Technology Policy Institute suggests there may not be a business appetite for commercial space station operations in Earth orbit. A view shared by NASA’s own Inspector General. Credit: Axiom International

Three potential markets for a commercial space station: the production of “exotic” optical fibres, satellite assembly and hosting astronauts from other national space agencies. However, the study found the potential revenues from these markets to vary from just US $7 million to $360 million per year, with a high level of uncertainty on the projections – although over an extended period, revenue would become more favourable. Even so, the study pointed out that, given the high cost of establishing orbital facilities, such uncertain projections are unlikely to attract venture capitalist investors, and the proposed US $900 million from NASA over 5 years insufficient to encourage commercial interest.

Alternatives to help kick-start a commercial presence in low-Earth orbit have been offered. The most obvious is to extend the current ISS programme through until 2028 while transitioning it over to private management. However, this would cost NASA some US $3-4 billion a year. A second option might be for NASA to subsidise a commercial space station in exchange for use of it, possibly at a cost of US $2 billion a year. However, both of these options would impact things like the lunar imitative the space agency has been directed to undertake.

NASA Inspector General Paul Martin has also expressed scepticism that the ISS could be transitioned to a viable commercial operation. “We question whether a sufficient business case exists under which private companies can create a self-sustaining and profit-making business using the ISS independent of significant government funding,” he said at the same congressional hearing. “The scant commercial interest shown in the station over its nearly 20 years of operation gives us pause about the agency’s current plans.”

It is possible the study and Martin’s view could influence further Senate support to keep the ISS operational beyond 2025.

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